This is a fix similar to 2d7d67cc, where slight plan alteration can
cause a random failure of this regression test because of an incorect
tuple ordering, except that this one involves lookups of pg_type.
Similarly to the other case, add ORDER BY clauses to ensure the output
order.

The failure has been seen at least once on buildfarm member skink.

Reported-by: Thomas Munro
Discussion: https://postgr.es/m/CA+hUKGLjR9ZBvhXcr9b-NSBHPw9aRgbjyzGE+kqLsT4vwX+nkQ@mail.gmail.com
Backpatch-through: 12